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Date: Tue, 6 Jan 2015 15:53:07 +0100
From: Michal Hocko <mhocko@...e.cz>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, Mel Gorman <mgorman@...e.de>,
Zhang Yanfei <zhangyanfei@...fujitsu.com>,
Minchan Kim <minchan@...nel.org>,
David Rientjes <rientjes@...gle.com>,
Rik van Riel <riel@...hat.com>,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Johannes Weiner <hannes@...xchg.org>,
Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH V4 3/4] mm: reduce try_to_compact_pages parameters
On Mon 05-01-15 18:17:42, Vlastimil Babka wrote:
> Expand the usage of the struct alloc_context introduced in the previous patch
> also for calling try_to_compact_pages(), to reduce the number of its
> parameters. Since the function is in different compilation unit, we need to
> move alloc_context definition in the shared mm/internal.h header.
>
> With this change we get simpler code and small savings of code size and stack
> usage:
>
> add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-27 (-27)
> function old new delta
> __alloc_pages_direct_compact 283 256 -27
> add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-13 (-13)
> function old new delta
> try_to_compact_pages 582 569 -13
>
> Stack usage of __alloc_pages_direct_compact goes from 24 to none (per
> scripts/checkstack.pl).
>
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> Cc: Mel Gorman <mgorman@...e.de>
> Cc: Zhang Yanfei <zhangyanfei@...fujitsu.com>
> Cc: Minchan Kim <minchan@...nel.org>
> Cc: David Rientjes <rientjes@...gle.com>
> Cc: Rik van Riel <riel@...hat.com>
> Cc: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
> Cc: Johannes Weiner <hannes@...xchg.org>
> Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
> Cc: Michal Hocko <mhocko@...e.cz>
Looks good as well.
Acked-by: Michal Hocko <mhocko@...e.cz>
> ---
> include/linux/compaction.h | 17 +++++++++--------
> mm/compaction.c | 23 +++++++++++------------
> mm/internal.h | 14 ++++++++++++++
> mm/page_alloc.c | 19 ++-----------------
> 4 files changed, 36 insertions(+), 37 deletions(-)
>
> diff --git a/include/linux/compaction.h b/include/linux/compaction.h
> index 3238ffa..f2efda2 100644
> --- a/include/linux/compaction.h
> +++ b/include/linux/compaction.h
> @@ -21,6 +21,8 @@
> /* Zone lock or lru_lock was contended in async compaction */
> #define COMPACT_CONTENDED_LOCK 2
>
> +struct alloc_context; /* in mm/internal.h */
> +
> #ifdef CONFIG_COMPACTION
> extern int sysctl_compact_memory;
> extern int sysctl_compaction_handler(struct ctl_table *table, int write,
> @@ -30,10 +32,9 @@ extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
> void __user *buffer, size_t *length, loff_t *ppos);
>
> extern int fragmentation_index(struct zone *zone, unsigned int order);
> -extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
> - int order, gfp_t gfp_mask, nodemask_t *mask,
> - enum migrate_mode mode, int *contended,
> - int alloc_flags, int classzone_idx);
> +extern unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
> + int alloc_flags, const struct alloc_context *ac,
> + enum migrate_mode mode, int *contended);
> extern void compact_pgdat(pg_data_t *pgdat, int order);
> extern void reset_isolation_suitable(pg_data_t *pgdat);
> extern unsigned long compaction_suitable(struct zone *zone, int order,
> @@ -101,10 +102,10 @@ static inline bool compaction_restarting(struct zone *zone, int order)
> }
>
> #else
> -static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
> - int order, gfp_t gfp_mask, nodemask_t *nodemask,
> - enum migrate_mode mode, int *contended,
> - int alloc_flags, int classzone_idx)
> +static inline unsigned long try_to_compact_pages(gfp_t gfp_mask,
> + unsigned int order, int alloc_flags,
> + const struct alloc_context *ac,
> + enum migrate_mode mode, int *contended)
> {
> return COMPACT_CONTINUE;
> }
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 546e571..9c7e690 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -1335,22 +1335,20 @@ int sysctl_extfrag_threshold = 500;
>
> /**
> * try_to_compact_pages - Direct compact to satisfy a high-order allocation
> - * @zonelist: The zonelist used for the current allocation
> - * @order: The order of the current allocation
> * @gfp_mask: The GFP mask of the current allocation
> - * @nodemask: The allowed nodes to allocate from
> + * @order: The order of the current allocation
> + * @alloc_flags: The allocation flags of the current allocation
> + * @ac: The context of current allocation
> * @mode: The migration mode for async, sync light, or sync migration
> * @contended: Return value that determines if compaction was aborted due to
> * need_resched() or lock contention
> *
> * This is the main entry point for direct page compaction.
> */
> -unsigned long try_to_compact_pages(struct zonelist *zonelist,
> - int order, gfp_t gfp_mask, nodemask_t *nodemask,
> - enum migrate_mode mode, int *contended,
> - int alloc_flags, int classzone_idx)
> +unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
> + int alloc_flags, const struct alloc_context *ac,
> + enum migrate_mode mode, int *contended)
> {
> - enum zone_type high_zoneidx = gfp_zone(gfp_mask);
> int may_enter_fs = gfp_mask & __GFP_FS;
> int may_perform_io = gfp_mask & __GFP_IO;
> struct zoneref *z;
> @@ -1365,8 +1363,8 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
> return COMPACT_SKIPPED;
>
> /* Compact each zone in the list */
> - for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
> - nodemask) {
> + for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
> + ac->nodemask) {
> int status;
> int zone_contended;
>
> @@ -1374,7 +1372,8 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
> continue;
>
> status = compact_zone_order(zone, order, gfp_mask, mode,
> - &zone_contended, alloc_flags, classzone_idx);
> + &zone_contended, alloc_flags,
> + ac->classzone_idx);
> rc = max(status, rc);
> /*
> * It takes at least one zone that wasn't lock contended
> @@ -1384,7 +1383,7 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
>
> /* If a normal allocation would succeed, stop compacting */
> if (zone_watermark_ok(zone, order, low_wmark_pages(zone),
> - classzone_idx, alloc_flags)) {
> + ac->classzone_idx, alloc_flags)) {
> /*
> * We think the allocation will succeed in this zone,
> * but it is not certain, hence the false. The caller
> diff --git a/mm/internal.h b/mm/internal.h
> index efad241..cd5418b 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -110,6 +110,20 @@ extern pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address);
> */
>
> /*
> + * Structure for holding the mostly immutable allocation parameters passed
> + * between functions involved in allocations, including the alloc_pages*
> + * family of functions.
> + */
> +struct alloc_context {
> + struct zonelist *zonelist;
> + nodemask_t *nodemask;
> + struct zone *preferred_zone;
> + int classzone_idx;
> + int migratetype;
> + enum zone_type high_zoneidx;
> +};
> +
> +/*
> * Locate the struct page for both the matching buddy in our
> * pair (buddy1) and the combined O(n+1) page they form (page).
> *
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index bf0359c..f5f5e2a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -232,19 +232,6 @@ EXPORT_SYMBOL(nr_node_ids);
> EXPORT_SYMBOL(nr_online_nodes);
> #endif
>
> -/*
> - * Structure for holding the mostly immutable allocation parameters passed
> - * between alloc_pages* family of functions.
> - */
> -struct alloc_context {
> - struct zonelist *zonelist;
> - nodemask_t *nodemask;
> - struct zone *preferred_zone;
> - int classzone_idx;
> - int migratetype;
> - enum zone_type high_zoneidx;
> -};
> -
> int page_group_by_mobility_disabled __read_mostly;
>
> void set_pageblock_migratetype(struct page *page, int migratetype)
> @@ -2421,10 +2408,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
> return NULL;
>
> current->flags |= PF_MEMALLOC;
> - compact_result = try_to_compact_pages(ac->zonelist, order, gfp_mask,
> - ac->nodemask, mode,
> - contended_compaction,
> - alloc_flags, ac->classzone_idx);
> + compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
> + mode, contended_compaction);
> current->flags &= ~PF_MEMALLOC;
>
> switch (compact_result) {
> --
> 2.1.2
>
--
Michal Hocko
SUSE Labs
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